1. Field of the Invention
The invention relates to protected filter units for safety filtration, in which the filter units with different packaging material are packaged at least twice, and a method for producing the protected filter units.
2. Description of the Related Art
Filter units are intended to be understood to be filter materials which in general are attached to filter material holders. Examples include prefabricated hollow-fiber filters and flat filters, filter candles, filter capsules, wound modules, filter cartridges, small filters such as syringe attachments, filters with unfiltrate and/or filtrate spaces or other filter units ready for connection. Safety filtrations are intended to be understood as those filtrations for which particular safety requirements are posed, such as sterile filtrations for retaining microorganisms, in particular bacteria, or filtrations in clean rooms, where the ingress of particles into said clean rooms, including into the gaseous and liquid media to be filtered, has to be avoided.
Sterile filter units which are loosely packaged individually in flexible bags are commercially available. Thus, DE 299 08 080 U1 describes single-use filter capsules for sterile filtration, prefabricated with connectors and single-use containers, which are loosely enclosed in a packaging. It is disadvantageous that, as a result of the loose packaging, grit is generated in the sterile product packaging space during the transport and the handling of the sterile filter units before use, and undesired particles are emitted from the packaging, and from the unpacked filter units when used in clean rooms, and into the media to be filtered. DE 101 54 702 A1 describes a reusable filter module packaging for sterile-filtering filter modules in which the filter units are fixed by specially designed fixing elements. It is disadvantageous that it is not permitted to unpack the filter units in clean rooms because the latter could be contaminated by the packaging. The filter units have to first of all be removed from the packaging in a separate area which is not part of the clean room. As a result of this, protected stockpiling of the filter units in the clean room area is not possible. DE 28 37 127 C2 describes an air-tight packaging, in particular for foodstuff, which is suitable for evacuation and/or gassing. It comprises a vat-shaped container made of a material which is sufficiently stiff for being stacked one above the other and which has on its inside a gas-tight film which holds the product to be packaged and which tapers off at the top into a flange-shaped peripheral edge, it being possible to close off the container by means of a closing sheet which can be attached to the film along the peripheral edge. The film forms a flexible inner packaging for the product, which is only attached to the container at its flange-shaped peripheral edge. The intermediate space between inner packaging and container is connected to the atmosphere via ducts. The inner packaging space can be gassed and/or made into a vacuum through the ducts, the ducts subsequently being sealed. Design and handling of the packaging is complex. It is unsuitable for filter units for safety filtrations because abrasion cannot be excluded during transport between filter unit and closing sheet and between inner packaging and housing. WO 87/05278 A1 describes an apparatus for transporting sterile articles in a double vat, each vat being sealed by a cover sheet which can be pulled off a circulating flange. To assist in the cover sheet of the inner vat being pulled off, a pulling-off band which can be gripped is attached to the latter. The rigid and complex design of the double vat is disadvantageous. It is unsuitable for filter units for safety filtrations because abrasion cannot be excluded during transport between filter unit and inner vat. DE 44 28 291 A1 discloses a single packaging for articles to be sterilized, in which the packaging surrounding the articles comprises a porous paper web and an impervious plastic film which are sealed to one another such that they can be peeled. The article can be sterilized by means of the paper web. DE 30 14 026 C2 discloses a further single packaging for articles to be sterilized, in which the packaging surrounding the articles comprises two impervious plastic films which are hot sealed to one another such that they can be peeled, it being possible to detect from the transparent or opaque look of the seal whether said seal was damaged. The laid-open patent application DE 2 217 793 discloses another single packaging for articles to be sterilized, which is composed of a special plastic film which is permeable to steam-type sterilization means but impermeable to pathogenic microorganisms, at least part of its surface being composed of an open-celled micro-porous polymer film which has a weight per unit volume which is less than the weight per unit volume of the corresponding polymer film which does not have an open-celled structure.
The above-mentioned apparatuses are unsuitable for filter units for safety filtrations because abrasion during transport between filter unit and inner vat cannot be excluded and single packaging can be easily damaged and this leads to a removal of the sterility of the filter units.
It is therefore the object of the invention to propose filter units for safety filtration which are protected until use and which themselves do not constitute a source of contamination, and a method for producing the same.